1. Field of the Invention.
The present invention generally relates to networking. More specifically, the present invention provides techniques and mechanisms for determining reverse path delay associated with a round trip time measurement.
2. Description of Related Art
Round trip time (RTT) is a commonly used networking metric for determining congestion between a source and a destination in a variety of networks. Networking tools and utilities allow a source to send data to a destination and the destination to respond to the source. The measured time between transmission of the data and receipt of the acknowledgment is referred to as the RTT. The RTT can be used by the source to estimate network congestion and latency between a source and a destination.
The RTT can also be used to set transmission rates and window sizes at a source. For example, if the RTT is relatively small, a source may interpret it as an indication of reduced network congestion and elect a higher transmission rate and a larger window size. Some improvements to TCP such as FastTCP described in “FastTCP: Motivation, Architecture, Algorithms, Performance” by Chen Jin, David Wei, and Steven Low, IEEE Infocom, March 2004, Hong Kong, explicitly use RTT to optimize window sizes.
However, using RTT as a metric for determining congestion has significant limitations. Consequently, it is desirable to provide techniques for improving the measurement of RTT components, such as reverse path delay or reverse delay components associated with RTT.